The present invention relates to servo operated valves and particularly servo operated rotary valves for use in an engine to control pressure pulse communication between different channels in an engine inlet manifold.
In the design and manufacture of engines for passenger cars and light trucks, it has been found desirable to provide alternate runners or channels in the engine inlet manifold for providing pressure pulse communication at different rates according to the engine operating speed and load. In particular it has been desired to prevent pressure pulse communication for use at low speeds and low loads; whereas for high speed or high loads it has been required to allow pressure pulse communication.
In known production engines for light vehicles, an electrically operated rotary vane valve has been employed in the engine manifold to control the opening and closing of such additional or secondary passages as required by the engine operating conditions. Such valves are typically installed through an access opening in the manifold to position the rotary vane at the inlet end of the secondary passages with the vane contacting a rib or stop surface provided in the manifold, for example, by integral molding therein. However, in view of the variation in dimensions between the parts and the variation in the positioning of the valve vane upon assembly into the manifold, it has been found difficult to provide a valve installation which eliminates pressure pulse communication in the secondary passages when the valve vane is in the closed position. This problem is particularly aggravated by the nature of the valve construction because it is required that the servo motor actuator for the valve be disposed externally of the airflow passage in the manifold. The valve must be assembled through an access opening in the manifold rather than built in during forming of the manifold.
Thus, it has been desired to provide an inexpensive relatively simple and easy to install diverter valve for an engine air inlet manifold which prevents residual pressure pulse communication in the secondary passages when the valve is in the closed position.